1. Field of the Invention
The present invention relates generally to rotors for electrical machines, and more specifically to routing of wire for field-generating coils of such rotors.
2. Description of the Related Art
In many electrical machines, a rotor includes an electromagnetic field generating coil which rotates with the rotor. In such machines, slip rings are typically provided as a part of the rotor assembly. The slip rings are means for connecting the field-generating coil to a source of electrical current.
Connection of the field generating coil to the slip rings can present reliability improvement opportunities in the design of a rotor for an electrical machine. For example, the two slip rings are typically manufactured as a single assembly, with two wires extending from the assembly. A first end of each wire is welded to a respective slip ring. A second end of each wire is welded to the wire which comprises the windings of the field-generating coil. The result is four interconnections between the field-generating coil and the slip rings. Although such designs have been honed to a relatively high degree of reliability, a reduction in the number of interconnections can improve reliability further.
An additional area of potential improvement in prior art designs is in the cost of the slip ring assembly. A typical slip ring assembly is manufactured by the aforementioned welding of wires to the copper slip rings, followed by insert-molding of this subassembly in plastic. The resulting slip ring assembly is a fairly expensive part, exhibiting considerable opportunity for cost reduction. An improved wire routing design from the field-generating coil to the slip rings may provide the ability to use more economical slip ring designs.
Therefore, wire routing designs for electrical machine rotors which can provide improved reliability and reduced cost can provide advantages over the prior art.